A Novel River Meander Migration and Cutoff Model: A New Perspective

Abstract

Accurate prediction of river meander migration is crucial for effective river management and operation, particularly in light of climate changes and human-induced interventions. Existing models often rely on single-equation approaches, such as bank erosion rate versus excess bank velocity or excess bank shear stress, which limit their ability to comprehensively capture the complex dynamics of meander evolution. This study presents a novel two-equation model for predicting river meander migration, representing a significant advancement in the fields of geomorphology, hydrology and river engineering. The proposed model introduces two coupled equations that comprehensively determine the movement of a point on the channel centreline capturing both the change in the channel centerline radius of curvature (r) and the change in the arc angle (θ). This approach provides a more holistic representation of meander migration compared to previous methods, allowing for a better understanding of the underlying physical processes. Furthermore, the paper presents an equation to estimate the critical discharge required for the occurrence of neck and chute cutoffs at a meander bend, incorporating the influence of channel geometry and flow characteristics. This contribution enhances the understanding of the cutoff process and its implications for river morphology. To validate the effectiveness of the meander migration model, two distinct case studies are considered: (1) Prediction of thalweg wavelength meandering in the Nile River, Egypt, where the model successfully captured the observed meander characteristics, demonstrating its accuracy in predicting large-scale meander patterns; and (2) Determination of river channel radius of curvature in four rivers in Texas, USA, where the model accurately predicted the radius of curvature in these diverse river systems, showcasing its applicability across different scales and environments. These results highlight the model's ability to accurately predict meander migration and cutoff events, making it a valuable tool for river management and planning.